Chennai: The December 2015 floods were result of failure of CMDA, the city development authority, to check large-scale construction along waterways and illegal conversion of agricultural land and water bodies, CAG said.

"Chennai Metropolitan Development Authority failed to check large-scale constructions along waterways, which choke waterways and altered land uses in metropolitan area," it said.

"Allowing conversion of agricultural land without government approval and unauthorised conversion of water bodies, non-urban and Open Space and Recreation land for various other purposes resulted in drastic changes in land use and thereby contributed to the floods," the CAG said.

People wade through a flooded road in Chennai in December, 2015. Reuters

The report of the Comptroller and Auditor General on 'Performance Audit of Flood Management and Response in Chennai and its Suburban Areas for the year ended March 2016' was tabled on the concluding day of the Assembly session on Tuesday.

The report also said the state lacked a law on Floor Plain Zone to protect natural waterways and water bodies have lesser storage capacity due to tardy implementation of restoration projects.

The December 2015 floods claimed 289 lives, inundate 23.25 lakh houses, disrupted power and telecommunication services, caused extensive damage to public and private property and brought the city to standstill for several days.

On encroachments, CAG said that despite enactment of law in 2007 (Tamil Nadu Protection of Tanks and Eviction o Encroachments Act, 2007) to protect tanks from encroachment the percentage encroachments kept increasing year after year.

"Encroachment of tanks, lakes and river beds played major role in causing the massive floods," it said.

It said tardy implementation of a project for restoration and protection of water bodies resulted in abandoning of lake and consequent reduction in water storage capacity of water bodies. CAG pointed out that the Tamil Nadu State Disaster Management Authority did not meet even once since its constitution in November 2013.

It said eight projects taken up under Jawaharlal Nehru National Urban Renewal Mission to provide new channels an strengthen existing ones in the metropolitan area could not be completed due to encroachments and lack of coordination between different departments.

"Inadequate coverage of Storm Water Drains (SWD) due to poor outlay, coupled with improper design and missing links in SWD networks, contributed to floods," the CAG report said.

Among recommendations made by CAG were expansion of Store Water Drain networks and enactment of a law on Flood Plain Zone on the lines suggested by the Centre.

"CMDA should not allow development along water bodies without ensuring ameliorating measures taken by developers to prevent the impact of such developments," the report said.

Explaining the post floods scenario, it said government conducted a special drive, evicting 4,531 of the 23,840 slum families along margins of the Adyar and Cooum rivers.

"Greater Chennai Corporation in 2016-17 took up works t construct 292 kilometre of SWD by earmarking Rs 463 crore. Th expenditure increased from by 159 percent," it said.